Distance measuring system



H. BUHLER DISTANCE MEASURING SYSTEM May 24, 1966 3,253,254

Filed Feb. 11, 1963 2 Sheets-Sheet 1 com/r512 4 E ,461 I 3 1 .3. 2 1 5 a6 7 5/61/41. 1 TRANSMITTER e d2 "I, 6 I

LAMP F I6. I I

e, :2 3 x a 26' FIG. 3 FIG. 4

INVENTOR.

llA/VSRUD/ 517m. ER

ATTORNEYS.

May 24, 1966 H. BUHLER 3,253,254

DISTANCE MEASURING SYSTEM Filed Feb. 11, 1965 2 Sheets-Sheet 2 COUNTER SIGNA L TRANS MIT INVENIOR. HANSRUDI SUI-IL ER A T TOR NE Y3.

United States Patent Claims priority, application Switzerland, Feb. 23, 1962,

2,291/62 7 Claims. c1. 340 23 This invention pertains, in general, to systems and apparatus useful in controlling vehicles; and, in particular, to a system and apparatus for determining the time at which the end of a rail-travelling vehicle passes a certain point on a track. I

Although the system and apparatus of the present invention is hereinafter described with reference to vehicles which are constrained to travel on rails (which may be conventional double-rail track or a monorail track), it is to be understood that the application of the present system and apparatus is not limited to vehicles constrained to travel on rails. The system and apparatus provided by the present invention are equally applicable and useful in connection with highway-travelling motor vehicles.

Often, it is necessary to maintain the speed of a railtravelling vehicle, such as a train, below a certain predetermined speed at certain sections of track, such as, for

example, at construction sites, curved sections of track, etc. After the end of the train has passed the track section, or zone, of limited maximum speed, it is safe to accelerate the rail-travelling vehicle or train. Very often,

however, the engineer is not able to determine when the end of the train has traversed the end of the limited-speed track section, or zone. For example, the engineers view may be obstructed during fog or while the train is traversing a curved section of track.

Accordingly, one object of the present invention is to provide a system and apparatus for indicating to the motorman, or engineer, when the end of the train has passed a certain predetermined point on the track section.

Another object of the present invention is to promote safety in 'connectionwith rail travel.

Another object of the present invention is to provide means for accomplishing the aforementioned objects simply, reliably and economically.

According to one illustrative embodiment of the present invention, there is'provided a measuring device, useful in'connection with rail-travelling vehicles, to determine the time at which theend of the train has passed a certain predetermined point on a track section. The subject measuring device is characterized by the use of a counter which is equipped with a preselector. Logic switching circuitry is employed in connection with the counter and preselector for actuating a signal transmitter which starts to operate as soon as the train has travelled a distance corresponding to the length of the train.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specfiic objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

In the drawings:

FIG. 1 is a block diagram of the measuring and controlling system according to one embodiment of the invention;

FIG. 2 is a schematic diagram of a multivibrator circuit representative of those employed in the embodiments of the invention illustrated at FIGS. 1 and 5;

FIG. 3 is a schematic diagram of an AND gate representative of those employed in the embodiments of the invention illustrated at FIGS. 1 and 5;

FIG. 4 is a schematic diagram of an OR gate representative of the one employed in the embodiment of the invention illustrated at FIG. 5; and

FIG. 5 is a block diagram of the measuring and controlling system according to another embodiment of the invention.

As is illustrated at FIG. 1, a switch 1, connected to the input of a monostable multivibrator 2, is intended to be actuated by the motorman or engineer as the front, or head of the train arrives at a point at the beginning of a slow-speed zone section of rail or track. An output a2 from monostable multivibrator 2 is connected to both the input of a counter 3 and to an input of a bistable multivibrator 6.

The counter 3 may be of known construction. For example, it may comprise a number of logic switching units to count the distance travelled by the train. At the input E of the counter 3 the necessary driving signals are received. The various counting stages a1, b1 indicate predetermined path distances. A selector switch, or preselector, 4 may be set to the appropriate counting stage a1, b1 which corresponds to the length of the train; the terminals a1, b1 being the output of the counter 3.

The selector switch 4, or preselector, is coupled to an input of an AND gate 5 via the input electrical path 11. The output path a5 of the AND gate 5 is connected with an input of the bistable multivibrator 6. The output a6 of the bistable multivibrator 6 is connected to an input of another monostable multivibrator 7, the output a7 of which serves to actuate an optical or acoustical signal transmitter 8. Also shown at FIG. 1 is an indicator lamp 9 which is for the purpose of indicating to the motorman, or the engineer, whether the measuring system is operating or not.

Before explaining in detail the operation of the system of FIG. 1, it will be helpful initially to explain the circuits illustrated schematically at FIGS. 2, 3 and 4.

FIG. 2 is a schematic illustration of a multivibrator circuit. (FIG. 2 will be used for the purpose of explaining the operation of both a monostable multivibrator and a bistable multivibrator.) The monostable multivibrator has two transistors 18 and 18. The emitters of these transistors are directly coupled with each other and with the terminal 0. The collector electrodes of the transistors 18 and 18' are coupled with each other, as shown, via the resistors 19, to the negative terminal of a source of potential and 19. Being unsymmetrically coupled, the multivibrator operation is monostable. Normally, the right-hand transistor 18 is conductive, but the transistor 18 can be blocked by introducing a positive voltage pulse at the input terminal 2. When this positive voltage pulse is introduced at the input terminal 2, transistor 18 then becomes conductive, via the feedback coupling represented by the capacitor 20 and the resistor 21. Subsequently, the capacitor 22 becomes charged so that, after a predetermined duration of time, the monostable multivibrator reverts to its normal condition; i.e., the transistor 18' is conductive and the transistor 18 becomes non-conductive. The normal condition of the monostable multivibrator circuit of FIG. 2 may, for convenience, be designated with regard to the potential conditions at the terminals shown at FIG. 2. For example, normally a=0 and a'=l; 1 being a predetermined negative potential. When apositive voltage pulse is introduced at terminal e, the normal condition of the monostable multivibrator is changed such that a=1 and a'==0. After a time which is determined by the RC circuit (resistor 23 and capacitor 22), the monostable multivibrator reverts to its normal condition; i.e., a= and a'=1.

A bistable multivibrator is arranged similarly to the monostable multivibrator shown at FIG. 2. However, the bistable multivibrator has a symmetrical feedback coupling and, thus, has two stable conditions rather than one stable condition, as in the case of the monostable multivibrator. As is known, one input pulse will change the bistable multivibrator from one stable condition to another stable condition; another input pulse being required to change the bistable multivibrator from the second stable condition back to the first stable condition. For convenience, the first stable condition of the bistable multivibrator is called the normal condition; the normal condition being a=0 and a'=,1. The second stable condition is such that a=1 and a=0.

FIG. 3 is a schematic diagram of an AND gate. Three diodes 25 are coupled in parallel between the terminals e1, e2, e3 and one terminal of the resistor 24, as shown. As is known, only when all of the input terminals e1, 22 and e3 have a negative potential introduced thereto, no current flows through the resistor 24 and thus the potential at the output terminal a is designated as 1; i.e., a=1.

However, if the potential at any one or two of the input terminals e1, e2 or e3 is 0, current flows through the resistor 24 and the potential at the output terminal a is .0; i.e., a=0. Thus, at the output terminal a of the AND gate of FIG. 3 there will occur a signala=1 only when all of the input terminals have negative input signals introduced thereto simultaneously.

At FIG. 4, there is illustrated in schematic diagram form an OR gate. Again, three diodes 25 are coupled in parallel between input terminals e1, e2 and e3, respectively and one terminal of a resistor 24. At the other end of the resistor 24 there is introduced a positive potential (indicated by the sign at FIG. 4). Accordingly, terminal a is at the potential condition such that a=1 only if there exists a negative potential at only one of the input terminals e1, e2, or e3.

Referring again to the system illustrated in the block diagram at FIG. 1, as long as the switch 1 is open, as illustrated, the following conditions prevail: a2=0; a2=1; 116:0; a6=1; 117:0; and a7=1. Since 426:0, the AND gate is blocked via the electrical path 10 so any signals from the counter 3 fed via the electrical path 11 through the preselector switch 4 cannot arrive via the output a5 of the AND gate 5 to the input of the bistable multivibrator 6. Thus, the signal transmitter 8 and the indicator lamp 9 are not operated.

According to the intended operation, the motorman, or engineer, sets the selector switch 4 on one of the appropriate terminals a1, b1 corresponding to the length of the train. The engineer actuates the switch 1 (closes the switch 1) as soon as the head, or front, of the train emerges from a predetermined point at the section of track at the end of the slow-speed zone. When the switch 1 is closed, a positive voltage impulse is supplied to the input e of the monostable multivibrator 2 which causes a tilting of the monostable multivibrator 2 for a few milliseconds. Accordingly, a2=1 and a2'=0. When the outputs a2 and a2 are in such a condition, the counter 3 is reset, thereby starting its counting operation. In addition, thebistable multivibrator 6 assumes the condition such that a6=1 and a6'=0. However, with respect to the monostable multivibrator 7, the condition a7=0 and a7'=1 is maintained. This condition is maintained because the change of 116:0 to a6=1 represents a negative voltage impulse which does not efiect any tilting of the monostable multivibrator 7. Since a6=1 the blocking of the AND gate 5 is discontinued and the indicator lamp 9 becomes lit, which indicates to the engineer or motorman that the measuring system and apparatus is in operation. After the train has covered a certain distance, which distance corresPOllSl 19 the length of the train, a counter signal from the counter 3 arrives at the appropriate output terminal a1, [)1 to which the preselector switch 4 has been set. From the preselector switch 4 the output signal is conducted, via the electrical path 11, to an input of the AND gate 5. From the output a5 of the AND gate 5 the signal is translated to an input of the bistable multivibrator 6. Accordingly, the bistable multivibrator 6 tilts into the condition such that (16:0 and a6: 1, which condition causes a positive voltage impulse and, therefore, results in the monostable multivibrator 7 being tilted. When the monostable multivibrator is thus tilted, the signal transmitter 8 responds, or is actuated, while the indicator lamp 9 is extinguished. Accordingly, the train can now be accelerated since the end of the train has passed or emerged from the end of a slow-speed zone. The signal transmitter 8 may be reset in any suitable manner well known to those familiar with the art.

If the system and apparatus according to the invention is to be used in a rail-travelling vehicle operated by but one motorman, or engineer, a system according to that shown in FIG. 5 is advantageous. As shown inFIG. 5, additional circuit elements have been added to the system shown in FIG. 1 to achieve the system shown in FIG. 5. In addition to the elements shown in FIG. 1, there is included a second switch 12, another monostable multivibrator 13, and the AND gate 14, a deadman switch 15, another monostable multivibrator 16 and another OR gate 17.

.It is customary in vehicles operated by a single motorman, or engineer, to reset a safety device and the counter 3 when certain control apparatus is actuated during the operation of the vehicle, such as, for-example, a brake valve, a foot pedal, etc. In such a case the contact 12 is closed and the impulse emanating from the monostable multivibrator 13 arrives via the AND gate 14 and the OR gate 17 at the counter 3 which is reset so that the control functions can be initiated. When the motorman, or engineer, has actuated the switch 1, a6'=0 and, as a result, the AND gate 14 is blocked. Therefore, disturbances of the measuring process can be avoided. However, if the engineer releases an element which is intended to be operated by him continuously, such as, for example, a push button or a pedal, for a certain duration of time, particularly when he is incapacitated, a deadman contact 15 is closed. Accordingly, an impulse from the monostable multivibrator 16 resets the counter 3 and the vehicle may be brought to a stop after a predetermined amount of time by a device (not shown) such as a clutch, brake, etc.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A distance measuring system, for indicating when a vehicle has travelled a predetermined distance, comprising: a first monostable multivibrator including an input terminal and an output terminal; a switch serially connected with the input terminal of said first monostable multivibrator; a counter including an input terminal and a plurality of output terminals, the output terminal of said first monostable multivibrator being coupled with the input of'said counter; an AND gate including two input terminals and an output terminal; a selector switch for coupling any one of the plurality of output terminals of said counter with an input of said AND gate; a bistable multivibrator having two input terminals and an output terminal, the output terminal of said first monostable multivibrator being coupled with one input terminal of said bistable multivibrator, the output terminal of said AND gate being coupled with the other input terminal of said bistable multivibrator; a second monostable multivibrator having an input terminal and an output terminal,

the output terminal of said bistable multivibrator being coupled with the input terminal of said second monostable multivibrator; circuit means interconnecting the output terminal of said bistable multivibrator with the other input terminal of said AND gate; and, indicator means connected with the output terminal of said second monostable multivibrator.

2. The measuring system, according to claim 1, wherein each of the plurality of outputterminals of said counter provides a different output signal representative of different distances travelled :by the vehicle, each different distance corresponding to a different length of vehicle.

3. The system, according to claim 1, wherein there is included a lamp connected with the output terminal of said bistable multivibrator to indicate operation of the system to the motorman,

4. The system, according to claim 1, wherein there is included additional safety means comprising: an OR gate including plural input terminals and an output terminal, said OR gate being interposed between said first monostable multivibrator and said counter, the output terminal of said first monostable multivibrator being coupled with one input terminal of said OR gate and with one input terminal of said bistable multivibrator, the output terminal of said OR gate being coupled with the input terminal of said counter; a third monostable multivibrator operable by a deadman switch to provide an output signal to another input terminal of said OR gate.

5. A completely vehicle-carried distance measuring system for indicating when the vehicle has travelled a certain distance, said system comprising, in combination, counting means receiving input signals representing increments of distance travelled by the vehicle, and providing output signals in counting stages each corresponding to a different certain distance travelled by the vehicle; second means selectively connectable to any one of said counting stages in accordance with a selected certain distance to he travelled by a vehicle; third means selectively actuable for starting said counting means; fourth means operable, responsive to actuation of said third means and to the output signal of said counting means, to provide another output signal; and fifth means operable, responsive to receipt of such other output signal from said fourth means, to indicate that the vehicle has travelled said selected certain distance corresponding to the distance set selectively by connection of said second means to a counting stage of said counting means.

6. A completely vehicle-carried distance measuring equipment for railroad rolling stock for determining the instant the tail end of the rolling stock passes a predetermined point along the path of travel of the rolling stock, said equipment comprising, in combination, a counter operable to receive input signals each representing an increment of distance travelled by the vehicle and to deliver output signals in counting stages each corresponding to different certain distance travelled by the vehicle; a distance selector switch selectively connectable to a selected one of said counting stages in accordance with the length of the rolling stock; signaling means; logic switching elements operatively associated with said counter, said selector switch and said signaling means to actuate said signaling means to indicate the instant the tail end of the rolling stock passes said predetermined point; and switch means operable by the driver of the rolling stock, when the head end of the rolling stock passes said predetermined point, to activate said measuring equipment; the driver having previously operated said distance selector switch to a position corresponding to the length of the rolling stock.

7. Measuring equipment as claimed in claim 6, said logic switching elements comprising a first mono-stable multi-vibrator; a bistable multi-vibrator; a second monostable multi-vibrator; said first mono-stable multi-vibrator having an output connected to said counter and to said bistable multi-vibrator; said first bistable multi-vibrator having an output connected to said second mono-stable multi-vibrator; said second mono-stable m-ulti-vibrator having an output connected to said signaling means to actuate the same; an indicating lamp connected to said bistable multi-vibrator; and an AND gate having a first input connected to said bistable multi-vibrator and a second input connected to said distance selector switch.

References Cited by the Examiner UNITED STATES PATENTS 2,460,597 2/1949 Rodgers 34023 2,623,163 12/1952 Bone et al. 340-31 2,702,367 2/1955 Ergen 32468 NEIL C. READ, Primary Examiner. A. H. WARING, Assistant Examiner. 

5. A COMPLETELY VEHICLE-CARRIED DISTANCE MEASURING SYSTEM FOR INDICATING WHEN THE VEHICLE HAS TRAVELLED A CERTAIN DISTANCE, SAID SYSTEM COMPRISING, IN COMBINATION, COUNTING MEANS RECEIVING INPUT SIGNALS REPRESENTING INCREMENTS OF DISTANCE TRAVELLED BY THE VEHICLE, AND PROVIDING OUTPUT SIGNALS IN COUNTING STAGES EACH CORRESPONDING TO A DIFFERENT CERTAIN DISTANCE TRAVELLED BY THE VEHICLE; SECOND MEANS SELECTIVELY CONNECTABLE TO ANY ONE OF SAID COUNTING STAGES IN ACCORDANCE WITH A SELECTED CERTAIN DISTANCE TO BE TRAVELLED BY A VEHICLE; THIRD MEANS SELECTIVELY ACTUABLE FOR STARTING SAID COUNTING MEANS; FOURTH MEANS OPERABLE, RESPONSIVE TO ACTUATION OF SAID THIRD MEANS AND TO THE OUTPUT SIGNAL OF SAID COUNTING MEANS, TO PROVIDE ANOTHER OUTPUT SIGNAL; AND FIFTH MEANS OPERABLE, RESPONSIVE TO RECEIPT OF SUCH OTHER OUTPUT SIGNAL FROM SAID FOURTH MEANS, TO INDICATE THAT THE VEHICLE HAS TRAVELLED SAID SELECTED CERTAIN DISTANCE CORRESPONDING TO THE DISTANCE SET SELECTIVELY BY CONNECTION OF SAID SECOND MEANS TO A COUNTING STAGE OF SAID COUNTING MEANS. 